A hermetic terminal of a refrigerant compressor is produced by sealing a metal stem and a metal pin to each other with a sealing material in order to maintain hermetic reliability.
The sealing material is produced and used as described below. First, a glass raw material is melted and formed, and the resultant formed body is pulverized in a ball mill and then allowed to pass through a predetermined sieve to provide fine powder. Next, granules are produced by mixing the fine powder with a binder and granulating the mixture. In some cases, the granules are obtained by adding and mixing ceramic powder to glass powder and granulating the resultant composite powder. After that, the resultant granules are subjected to tablet molding to produce a green compact having a through-hole, and the green compact is increased in temperature from normal temperature, to thereby decompose and remove the binder and sinter the green compact. Next, a metal pin is inserted in the through-hole of the resultant sintered compact, and the sintered compact is in turn housed in a circular metal stem, followed by being loaded into a firing furnace, and fired at a temperature higher than a glass transition point under an inert atmosphere or a nitrogen atmosphere, to thereby seal the metal pin and the metal stem to each other. As a result, the sealing material is in a state of being compressed by the metal stem. The metal stem generally has a linear thermal expansion coefficient of 140×10−7/° C. The metal, pin generally has a linear thermal expansion coefficient of from 100×10−7/° C. The sealing material generally has a linear thermal expansion coefficient of from 89×10−7/° C. to 95×10−7/° C.
FIG. 1A is a conceptual diagram for illustrating a hermetic terminal 1. The hermetic terminal 1 comprises a metal stem 11, a metal pin 12, and a sealing material 13. FIG. 1B is a conceptual diagram for illustrating, with respect to a main portion of the hermetic terminal 1 of FIG. 1A, a state of the metal stem 11, the metal pin 12, and the sealing material 13 before firing. FIG. 1C is a conceptual diagram for illustrating, with respect to the main portion of the hermetic terminal 1 of FIG. 1A, a state of the metal stem 11, the metal pin 12, and the sealing material 13 after the firing.